Tampering with multipart negotiable instruments, such as checks, drafts, and tickets, such as airline tickets, by altering the amounts or destinations, or other information causes great monetary losses to the enterprises issuing them. Although various proposals have been made to alleviate this problem, they have not been entirely successful.
A new system which is the subject of U.S. patent application Ser. No. 389,216, filed June 17, 1982 and which is owned by the assignee of the present application has met with enthusiastic commercial acceptance. It has provided a system of alteration detection which is a substantial improvement over the other prior art systems. In that system multipart negotiable instruments are prepared that have improved resistance to tampering after images are applied thereto. In that system, an instrument is comprised of at least a first and a second generally planar web, each web defining a first and a second surface. The second surface of the first web includes a means for transferring an image to a surface in contact therewith when a corresponding image is inscribed upon the instrument. The second web is secured in stacked relation to the first web and its first surface is in contact with the second surface of the first web. The first surface of the second web includes a layer for receiving an image that is in register with at least a portion of the image transferring means of the first web, and which is capable of receiving an image from the image transferring means of the first web when a corresponding image is inscribed on the instrument. The image receiving layer comprises a particulate matrix that is erasably bonded to the second web and is defaced when rubbed with organic solvent. The image receiving layer is also readily removable when a adhesive coated tape having a bond strength to steel of at least about 5 ounces per linear inch is bonded to the sheet and then pulled away.
Such multipart instruments are prepared by providing a first, generally planar web defining a first and a second surface. A material for transferring images is applied as a coating to the second surface of the first web to form an image transferring means. The transferring material is applied in an amount sufficient to transfer an image corresponding to one that is inscribed on the instrument, as upon the first surface of that web, to an image receiving layer on a second web in contact with the second surface of the first web. A second, generally planar web defining a first and a second surface is also provided. A coating or image receiving layer comprised of a particulate matrix erasably bonded to the web is applied to the first surface of the second web. The image receiving layer is defaced when rubbed with an organic solvent and is also removable when a adhesive coated tape having a bond strength, as of 5 ounces per linear inch, is affixed to it and then pulled away. The first and second webs are secured together in a stacked relation so that at least a portion of the image transferring means on the second surface of the first web is in contact and in register with at least a portion of the image receiving layer on the first surface of the second web.
Although this system is effective to provide a visual indication of tampering or alteration when one uses reasonable care to examine the tickets, unfortunately ticket takers too frequently, as in their rush to board passengers, fail to examine the tickets for forgery, thus allowing altered tickets to be used. Although it would be of advantage to provide a machine readable indication of alteration, the improved tickets of application Ser. No. 389,216 are not, in their present form, machine readable to identify alterations. Thus, the art does not yet supply a fully satisfactory means for readily identifying and therefore resisting tampering with the images on multipart negotiable instruments such as airline tickets.